Derrangements

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There are N people who live in N different houses, such that P1 lives in house H1, P2 lives in H2 and so on. Your task is to send every person into a different house such that P1 does not go to house H1, P2 does not go to house H2.... and person Pk does not go to house Hk and others can go to any house. Given N and k, how many such different arrangements are possible. If no such arrangement is pos

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solution.cppC++17

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